Google hasn’t taken that route in real world conditions. That TGV-TGV routing is nice but also more expensive; often you have to connect to regional, non-TGV trains. And, you also have train station transit/check in times too. Not everyone lives next to the St. Charles station in Marseille. From check-in counter to gate, it rarely takes longer than 15 minutes at the Marseille Airport. Took me 30 minutes once because of a slow passport line, but outside the major hubs, airport check in isn’t much slower than trains. Airports have the added benefit of being safer. There have been several knife and acid attacks at the St Charles train station. Pickpockets are ubiquitous.

But still, a 45 minute flight versus 4 hours with a connection on a train at a similar cost..